1. Field
The present disclosure relates to methods and apparatuses for detecting and controlling a fluid in a microfluidic device. More particularly, the present disclosure relates to methods and apparatuses for rapidly and exactly determining whether a fluid at a particular position of a micro-channel in a microfluidic device is a liquid or a gas, and for controlling movement of the fluid in the microfluidic device based on the determination regarding the state of the fluid.
2. Description of the Related Art
According to developments in a personalized medical care, procedures such as genetic analysis, extrasomatic diagnosis, genetic nucleotide sequence analysis, and the like have become important, and the need for them has increased. Accordingly, a system capable of rapidly performing many tests by using a small sample amount is being developed and commercialized. Also, in order to embody the system, a microfluidic device, such as microfluidics or a lab-on-a-chip (LOC), is being highlighted. The microfluidic device including a plurality of micro-channels and a plurality of micro-chambers is designed to control and to handle a very small amount of fluid (e.g., a fluid in the range of about several nl (nanoliters) to about several ml (milliliters)). By using the microfluidic device, a reaction time of a microfluid may be minimally decreased, and reaction of the microfluid and measurement of a result thereof may be simultaneously performed. The microfluidic device may be manufactured by using various methods, and various materials are used according to the various methods.
The microfluidic device includes a plurality of micro-chambers in which reactions occur and a plurality of micro-channels for providing a sample or a reagent to the plurality of micro-chambers. Thus, in order to control movement of the sample or the reagent to a desired place, it is necessary to exactly detect a state of each micro-channel and a state of a fluid (i.e., liquid or gas) in the plurality of micro-channels. However, because a size of each micro-channel and a size of each micro-chamber of the microfluidic device are in the range of about several tens of μm (micrometers) to about several hundreds of μm, it is difficult to rapidly and exactly detect the state of the fluid.
Examples of currently proposed fluid detection methods include a method of disposing a plurality of electrodes in a micro-channel and then detecting a state of a fluid by measuring resistance variation between the electrodes, and a method of capturing an image of a portion of a micro-channel and then determining a state of a fluid via an image processing operation. In the case of the method of using electrodes, it is difficult to dispose the electrodes in the micro-channel, the manufacturing costs of a microfluidic device may increase, and there is a possibility that a sample or a reagent may be contaminated. In the case of the method of capturing an image, there is a spatial limit due to disposal of an image-capturing device and lighting, and a determination speed may be decreased due to the image processing operation.